What kind of prop are running and what kind of speeds/RPMs do get out of it?
Wailana = Old Martec 2 bladed ungeared folder = 5.5 kts under power with no wind at 2800 RPM but we cruise at 5 kts. at 2600 RPM. Now that’s with a clean bottom with no dinghy.
Anything over 2600 and we get a loud and shaky vibration.